Atomic Absorption

Terry A. Ring

Chemical Engineering

University of Utah

E= -13.6 eV Z2/n2

Photo absorption/emision

Atomic Absorption

Lamps are Special

• Cathode with receptacle for material

• Vapor of Material to be analyzed

• Vapor Excited by plasma

• Light of particular wavelength

Aerosol Flow

• Burner Fuel (& oxidizer) mixed with aerosol of sample

• Sample asperated into burner

• Flame ionizes Sample

Intensity vs Wavelength in AA

• Light Source

• Absorbance

• Monochromatic

• Detector

Analysis

• Absorption of Light

• Electrons are excited

• Light Intensity on detector is less

Graphite furnace AA

Other AA’s

• Flame

• Spark

• Arc

• Plasma

• Laser

• X-ray

Atomic Emission Spectroscopy• Flame is used to

generated Atoms with excited electrons and ions

• Light is filtered in spectrometer to give Intensity vs wavelength

Spectrometer

• Emitted Light

• Broken into different color components– Prism– Grating

X-ray Fluorescence

• Two Steps– Absorption of X-ray

• Elimination of electron for k or L shell

– Collapse of M shell electron to fill hole

• Light emission (x-ray)

Potential X-ray Emissions

• From K shell hole– K, K, K,

– Zeeman Effect - 1, 2, 3

• From L shell hole– L, L, L,

Generation of X-rays

• High Voltage Electrons

• Electron Scattering

• Electron Absorption– X-ray photo

ionization

XRF

• Energy-dispersive XRF

• Wavelength-dispersive XRF

XRF Detectors

• Energy-dispersive XRF– Semiconductor

• Wavelength dispersive XRF– Scintilation Counter

XRF Analysis

• Samples can be in any form– Solid– Powder– Liquid